NOAA Technical Report NMFS 101 March 1991

Larvae of Nearshore Fishes in

Oceanic Waters near Oahu, Hawaii

Thomas A. Clarke

U.S. Department of Commerce
NOAA Technical Report NMFS _

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73. Marine flora and fauna of the Eastern United States. Mollusca:

Cephalopoda, by Michael Vecchione, Clyde F. E. Roper, and Michael

J. Sweeney. February 1989, 23 p.

74. Proximate composition and fatty acid and cholesterol content of22

species of northwest Atlantic finfish, by Judith Krzynowek, Jenny Murphy, Richard S. Maney, and Laurie J. Panunzio. May 1989, 35 p.

75. Codend selection of winter flounder Pstudopleuronectes amerieanus, by

David G. Simpson. March 1989, 10 p.

76. Analysis of fish diversion efficiency and survivorship in the fish return

system at San Onofre Nuclear Generating Station, by Milton S. Love,

Me«:nu Sandhu, Jeffrey Stein, Kevin T. Herbinson, Robert H. Moore,

Michael Mullin, and John S. Stephens Jr. April 1989, 16 p.

77. Illustrated key to the genera of free-living marine nematedes of the

order Enoplida, by EdwinJ. Keppner and Armen C. Tarjan. July 1989,

26 p.

78. Survey of fishes and water properties of south San Francisco Bay,

California, 1973-82, by Donald E. Pearson. August 1989, 21 p.

79. Species composition, distribution, and relative abundance of fishes

in the coastal habitat off the southeastern United States, by Charles A.

Wenner and George R. Sedberry. July 1989, 49 p.

80. Laboratory guide to early life history stages of northeast Pacific fishes,

by Ann C. Matarese, Arthur W. Kendall Jr., Deborah M. Blood, and

Beverly M. Vinter. October 1989, 651 p.

81. Catch-per-unit-effort and biological parameters from the Massachusetts coastal lobster (Homarus amerieanus) resource: Description and Trends,

by Bruce T. Estrella and Daniel J. McKiernan. September 1989, 21 p.

82. Synopsis of biological data on the cobia Rochycentron canadum (Pisces:

Rachycentridae), by Rosalie Vaught Shaffer and Eugene L. Nakamura.

December 1989, 21 p.

83. Celaphopods from the stomachs ofsperm whales taken off California, by Clifford H. Fiscus, Dale W. Rice, and Allen A. Wolman. December 1989, 12 p.

84. Results of abundance surveys ofjuvenile Atlantic and Gulf menhaden, Brevoortitl tyrannus and B. patrunus, by Dean W. Ahrenholz, James F.

Guthrie, and Charles W. Krouse. December 1989, 14 p.

85. Marine farming and enhancement: Proceedings of the Fifteenth

U.S.-Japan Meeting on Aquaculture, Kyoto, Japan, October 22-23, 1986,

edited by Albert K. Sparks. March 1990, 127 p.

86. Benthic macrofauna and habitat monitoring on the continental shelf

of the northeastern United States. I. Biomass, by Frank St~imle. February 1990, 28 p.

87. Life history aspects of 19 rockfish species (Scorpaenidae: Sebastes) from

the Southern California Bight, by Milton S. Love, Pamela Morris, Merritt McCrae, and Robson Collins. February 1990, 38 p.

88. Early-life-history profiles, seasonal abundance, and distribution of

four species of clupeid larvae from the northern Gulf of Mexico, 1982 and

1983, by Richard F. Shaw and David L. Drullinger. April 1990, 60 p.

89. Early-life-history profiles, seasonal abundance, and distribution of

four species of carangid larvae off Louisiana, 1982 and 1983, by Richard

F. Shaw and David L. Drullinger. April 1990, 37 p.

90. Elasmobranchs as living resources: Advances in the biology, ecology,

systematics, and the status of the fisheries, edited by Harold L. PrattJr.,

Samuel H. Gruber, and Toru Taniuchi. July 1990, 518 p.

91. Marine flora and fauna of the northeastern United States, Echinodermata: Crinoidea, by Charles G. Messing and John H. Dearborn. August

1990, 30 p.

92. Genetics in aquaculture: Proceedings of the sixteenth U.S.-Japan

meeting on aquaculture, Charleston, South Carolina, October 20-21, 1987,

edited by Ralph S. Svrjcek. November 1990, 81 p.

93. Distribution and abundance of juvenile salmonids off Oregon and

Washington, 1981-1985, by William G. Pearcy and Joseph P. Fisher.

November 1990, 83 p.

94. An economics guide to allocation of fish stocks between commercial and recreational fisheries, by Steven F. Edwards. November 1990, 29 p.

95. Larval fish recruitment and research in the Americas: Thirteenth

annual larval fish conference, Merida, Mexico, May 21-26, 1989, edited

by Robert D. Hoyt. January 1991, 137 p.

96. Marine flora and fauna of the Eastern United States. Copepoda,

Cyclopoida: Archinotodelphyidae, Notodelphyidae, and Ascidicolidae, by

Patricia L. Dudley and Paul L. Illg. January 1991, 40 p.
NOAA Technical Report NMFS 101

Larvae of Nearshore Fishes in

Oceanic Waters near Oahu, Hawaii

Thomas A. Clarke

March 1991

u.s. DEPARTMENT OF COMMERCE

Robert Mosbacher, Secretary

National Oceanic and Atmospheric Administration

John A. Knauss, Under Secretary for Oceans and Atmosphere

National Marine Fisheries Service

William W. Fox Jr., Assistant Administrator for Fisheries
The National Marine Fisheries Service (NMFS) does not approve,

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Text printed on recycled paper

11
Larvae of Nearshore Fishes in

Oceanic Waters near Oahu, Hawaii

THOMAS A. CLARKE

Department oj Oceanography and

Hawaii Institute oj Marine Biology

University oj Hawaii

p. 0, Box 1346

Kaneohe, HI 96744

ABSTRACT

Larvae of over 50 families of nearshore fishes were taken in oceanic waters about 13 km offshore of the leeward (southwest) coast of Oahu, Hawaii during 1977-78, The five most frequently

taken families (Labridae, Parapercidae, Serranidae, Gobiidae, and Carangidae) made up over

50 % of the total nearshore larvae. Most other families were taken very infrequently. Comparison

of catch data from three types of nets indicated that 1.25-m diameter bongo nets often sampled

larvae as well or better than a 3-m Isaacs-Kidd trawl and that smaller, 70-cm diameter bongo

nets were often as effective as the larger nets for certain abundant taxa. Only a few taxa showed

evidence ofseasonal patterns in abundance. Irregular temporal variability in abundance ofsome

taxa may have been related to occasional recent influxes of surface water from closer to shore.

Most larvae taken were late preflexion stage or older. Densities of even the most abundant taxa

were rarely greater than 0.001 m- 3• The nearshore fish larvae were not dominated by taxa with

large larvae or with larvae possessing apparent specializations to pelagic existence, Most taxa

taken were pelagic spawners as adults, but larvae of demersal spawners were roughly as well

represented as demersal spawners are among the nearshore fish fauna. Previous studies of waters

closer to shore probably sampled insufficient volumes for any but a few exceptionally abundant

taxa. Sampling with volumes filtered of the order of 104

-105 m3 will be necessary to determine

if the dominant taxa taken by the present study are ever more abundant closer to shore,

Introduction

Most species of nearshore marine fishes have pelagic eggs

or larvae which are subject to dispersal away from adult

habitat. Consequently, recruitment to adult populations

is controlled not only by survival during the pelagic stages

but also by the probability of return of premetamorphoric

larvae to inshore areas suitable for settlement. The role of

egg and larval dispersal in the population dynamics of

tropical inshore fishes has recently received much attention (McFarland and Ogden 1985). Losses due to dispersal away from suitable habitats may be more important

in limiting recruitment of nearshore fish populations of

steep sloped oceanic islands than populations along more

extensive and broader continental coastlines (Walsh 1987).

For the most part, aspects or consequences of dispersal have

been inferred from shore-based studies of spawning and

recruitment (Victor 1984), adult life-history characteristics

(Barlow 1981), or ages of settlement estimated from otolith

increments (Brothers and Thresher 1985). There is little

direct knowledge ofthe distribution, density, and size composition of larvae of inshore fishes,

Most available data on fish larvae near oceanic islands

are from relatively close to shore. Leis (1982) found that

larvae within a few km of shore in Hawaii were dominated by a few species, most of which were demersal

spawners. Larvae of most common inshore fish families

with pelagic eggs were rare or absent. Larvae of several

inshore families have been reported from oceanic waters

well removed from adult habitats (Richards 1984), and

some inshore taxa have larvae with apparent adaptations

to pelagic existence (Leis and Rennis 1983), Based on

abundance of certain groups of larvae relative to total larvae

in a series of samples from Hawaii, Leis and Miller (1976)

concluded that larvae of inshore families which spawn

demersal eggs were more abundant close to shore and that

larvae of families which spawn pelagic eggs were more

abundant offshore. They did not, however, provide or compare actual densities of different types of larvae from different locations. In fact, there are few quantitative data
2 NOAA Technical Report NMFS 101 _

available on densities oflarvae of inshore fishes in oceanic

waters.

This paper reports on the larvae of inshore fishes taken

in oceanic waters near the Hawaiian Islands. The larvae

were taken during a 16-month long program that repeatedly sampled the upper layers with three different types

of nets. Although the program was originally designed for

investigation of vertically migrating oceanic fishes and the

collections were dominated by oceanic taxa, larvae of

inshore taxa were also regularly taken. The data on the

latter provide the opportunity for more quantitative consideration of composition, abundance, and seasonality than

was previously available for offshore waters and also permit more definitive comparison with data from areas closer

to shore.

Methods _

All samples were taken along a track roughly parallel to

and ca. 13 km off the leeward coast of the island of Oahu,

Hawaii (between 21°18'N, 158°15'W and 21°30'N,

158°23'W). Water depth along the transect was 2000 m

or greater, and the macrozooplankton and micronekton in

the area were dominated by oceanic species (Clarke 1980).

Samples were taken on short cruises between August 1977

and October 1978. Most cruises were within 1-2 days of

new moon of each lunar month during the period. Because

of scheduling difficulties, there was no cruise in January

1978; the cruise for November 1977 was 4-5 days after full

moon; and the cruise for February 1978 was at full moon.

Thus 15 of the 16 lunar months covered were sampled,

and 13 at or close to new moon. The cruises are subsequently referred to by year and month, e.g., 78-03 for

March 1978. (New moon occurred twice in October 1978.

For convenience, the cruise during the second new moon

was designated 78-11 in spite ofthe fact that the cruise was

during the last days of October.)

Nighttime oblique tows were taken with three types of

nets. Detailed descriptions of the gear and procedures are

given in Clarke (1983) and are only briefly summarized

here. A 3-m Isaacs-Kidd midwater trawl (IK) with a body

of ca. 6-mm mesh netting was towed at ca. 2 m/sec and

fished between the surface and a mean maximum depth

of 325 m. A large bongo net frame (BB) with 1.25-m

diameter nets of ca. 2. 5-mm mesh netting was towed at

ca. 1.75 m/sec between the surface and a mean of 304 m

depth. A standard 70-cm diameter bongo frame (SB) with

nets of either 0.333- or 0.183-mm mesh netting was towed

at ca. 1 m/sec between the surface and a mean of 224 m

depth.

On most cruises, four IK tows were taken during the

first night, and two BB plus four SB tows during the

second. The IK tows, which covered ca. 12 km each, essentially sampled the entire transect twice (two tows along a

roughly NNW course and two return tows on the reciprocal

course). The BB tows, which covered ca. 10 km each,

sampled the southern half of the transect twice (one tow

headed NNW and the second on the reciprocal course).

The SB tows, which only covered ca. 2 km each, were all

taken sequentially along the southern end of the transect.

The exceptions to the standard sampling were: only three

IK tows on 77-09 and 77-12, no BB tows on 77-12, and

only two or three SB tows on the first five cruises (77-8

through 77-12). Additionally, two IK samples were taken

during each of two other cruises in the same area at full

moon in both March and April, 1978. A total 62 IK

samples, 28 pairs of BB samples, and 50 pairs of SB

samples were examined.

All nets were equipped with flowmeters and time-depth

recorders. For the few cases where one or the other device

malfunctioned, the missing value of either flow or maximum depth was estimated from plots of flow vs. maximum

depth of the satisfactory tows. Volumes sampled were

determined from flowmeter data and mouth area. Because

the sampling program was originally designed for vertically

migrating mesopelagic fishes, the maximum depths were

purposefully much greater than needed for sampling of inshore fish larvae. Current studies with opening-closing nets

(Boehlert and Mundy, NMFS, Honolulu Laboratory) as

well as preliminary analyses of nearshore fish larvae from

many horizontal IK tows taken in the study area from 1969

to 1974 indicate that few, if any, occur deeper than ca.

100 m. Consequently, the total volume sampled by each

tow was multiplied by the ratio of 100/maximum depth to

provide the volume sampled in the upper 100 m only, a

more appropriate value for this study.

The means (and ranges) of volumes sampled in the upper

100 m per tow by each type of net were IK-31,919 m3

(23,400 - 56,250 m3); BB (both nets)-6582 m3 (3450 -

15,200 m3); SB (both nets)-781 m3 (326 - 1604 m3).

For each type of gear, the variability in volume filtered per

tow was almost exclusively due to variability in flowltime

(as opposed to deviations from the wire out schedules or

total duration of tow) and was apparently caused by unexplained variation in the ship's speed. The effect was

compounded because maximum tow depth was inversely

correlated with flow/time. Consequently, both the volume/

tow and the ratio of 100/maximum depth were higher for

faster tows.

There were also great differences in the relative volumes

filtered per cruise by each type of gear. For individual

cruises, the IK tows filtered 6.5-20.4 times the volume

filtered by the BB tows and 23.5-83.9 times that filtered

by the SB tows. Overall the IK tows filtered 10.53 times

the volume filtered by the BB tows and 46.88 times that

by the SB tows. The volume filtered by the BB tows was

3.3-12.3 times the SB volume for individual cruises and

4.45 times the SB volume overall. For the 13 cruises where

at least three SB tows were taken, the range of BB:SB
_________________________ Clarke: Larvae of Nearshore Fishes near Oahu, Hawaii 3

volumes filtered was 3.5-6.8. (The above comparisons

involving the BB exclude 77-12 when no BB tows were

taken.)

Samples were preserved and held in 4% formaldehydeseawater solution. The IK samples were sorted under 3 x

magnification. Subsequent rechecking ofselected samples

under a dissecting microscope at lOx indicated that

negligible numbers of fish larvae over 5-6 mm long and

5-10 % of the smaller larvae were missed by the routine

procedure. The BB and SB samples were sorted under a

dissecting microscope at lOx . Rechecking indicated that

practically no fish larvae were missed by routine sorting.

Standard lengths or, for preflexion larvae, notochord

lengths were measured to the nearest 0.5 mm. For both

types of bongo samples, the catches and volume sampled

from both nets combined were used for analyses and

presentation. The SB samples with 0.183-mm nets obviously retained smaller larvae than those with 0.333-mm

nets, but since such small larvae attributable to nearshore

families were so infrequent in the samples, the data from

both types of SB samples were pooled for analyses.

Fish larvae from inshore taxa were separated from those

of oceanic groups. The latter, mostly myctophids and

stomioids, usually constituted over 90% of the total larvae. Two major groups which are solely or partly inshore,

the Pleuronectiformes and Anguilliformes, were not further identified and are not considered in this paper. Almost

all late preflexion and postflexion larvae were readily identifiable to either nearshore or oceanic taxa, and the former

were usually identifiable to family. Among the very small

«2-3 mm) early preflexion larvae there were a substantial number that I did not definitely class as either oceanic

or nearshore. Based on my observations of larger, identifiable oceanic larvae during the sorting and identification process, the great majority of these "unknown"

preflexion larvae were probably of oceanic perciform or

perciform-like taxa, such as melamphaids, Howella spp. and

similar epigonids, stromateoids, or perhaps even some

myctophiforms, whose very early larval stages have not

been described. These unknown preflexion larvae were

smaller and less-developed than the smallest identifiable

specimens of most nearshore taxa, and there were no

apparent "connecting links" between them and larger

nearshore larvae in the material. (Fairly continuous series

of sizes and developmental stages were present for the

few nearshore taxa whose size range included very small

larvae.)

Identification of nearshore larvae below family was

variably possible. Many families taken almost certainly

included more than one form oflarvae, but numbers were

too low to assemble definitive series for reliable discrimination. In other cases, distinct forms were evident and often

attributable to genera or species known from Hawaii based

upon meristics, previously published descriptions, or

developmental series that were assembled from available

material. In many families, where the meristics of different

genera or species overlap, tentative or "most likely" identifications of different forms were based upon frequency

distribution of counts. Frequently, forms could not be

discriminated from each other at the smallest sizes. For

most larvae identified to genus it was usually not certain

that either one or more than one species were included;

consequently, I have omitted the conventional "sp." or

,'spp. " after generic names.

Most nearshore taxa were taken very infrequently, and

even for the abundant taxa, data from all cruises were

pooled for density estimates and between gear comparisons.

Even then, total catches of the SB and often the BB were

5 for many taxa and considered inadequate for further

analyses. Catches of a few very abundant taxa were high

enough for meaningful comparison of densities and size

composition between cruises with high catches and the remainder ofthe data. Otherwise, numbers were too low and

variability too high for meaningful within or between cruise

comparisons. Size compositions were compared using the

Kolmogorov-Smirnoff test; differences were considered

significant if the resultant probability was 0.05. Interpretation of differences in density estimates was very conservative. Differences of less than ± 50% were considered

likely to be due to chance and small numbers, and the data

were carefully examined to assure that apparent differences

were not due to one or two extremely high catches.

Results _

A total of 5192 larvae were definitely and 74 tentatively

identified to one of 53 families of nearshore fishes. Some

families could be further broken down into size groups,

lower taxa, or recognizably different forms, with the end

result of 122 different categories of nearshore larvae

(Table 1). Additionally there were two unidentified forms

of larvae, each represented by seven individuals, which

were probably nearshore forms but whose meristics were

unattributable to any known Hawaiian families. (One of

the unidentified forms resembled uranoscopelids most

closely and the other, apogonids.) Only 26 postflexion

specimens, some damaged, were neither clearly of oceanic

families nor definitely attributable to any nearshore family,

but there were 550 "unidentified preflexion" larvae.

The nearshore larvae were dominated by a few forms

(Table 2). The 20 most abundant families made up over

90% of the total. The Labridae alone accounted for almost

25 % of the total, and the five most abundant families accounted for over half. Among lower taxa, Parapercis, Labrid

S, and Luzonichthys earlei made up almost 25 % of the total

larvae, and the top twen ty forms made up over 50 % . For

the great majority of larval forms listed in Table 1, the

numbers of specimens collected were so few that further

comment beyond the record of their numbers and size
4 NOAA Technical Report NMFS 101

Table 1

Numbers and size ranges of nearshore fish larvae collected from oceanic waters near Oahu, Hawaii during 1977-78. For each

taxon, the number and size range of positively identified specimens are followed by the number and size range of specimens

that could only be tentatively identified ("No. ?").

Size Size l Size Size

Taxon No. (mm) No.? (mm) Taxon No. (mm) No.? (mm) I

Argentinidae Malacanthidae 4 (10.5- 34) (3.5)

Glossanodon struhsakeri 2 (8 - 8.5) 2 (3 - 4) Pomacanthidae

Synodontidae 6 (4-15) Centropyge 26 (2.5 -5)

Trachinocephalus myops 23 (6.5 - 32) Centropyge L3 102 (4 - 22) 9 (14-21)

Synodus 169 (4.5-40) 5 (4.5-17) Centropyge S3 17 (6- 20) 3 (20- 21)

Chlorophthalmidae 8 (8-65) 1 (11) Priacanthidae 1 (10) 1 (6.5)

Moridae 1 (39) Serranidae 21 (2 - 5) 9 (2.5 - 4)

Carapidae 29 (13-75) Luzonichthys earlei 260 (4-31)

Ophidiidae Serranid A 70 (5 - 18)

Bratula multibarbata 16 (3.5-60) 2 (3-3.5) Serranid B 12 (5 - 27)

Ophidiid X 14 (6.5-40) Serranid C 12 (4 - 22) (5)

Antennariidae 20 (2.5-12) Serranid A' 3 (4-4.5)

Ogcocephalidae 5 (3-6.5) (2.5) Serranid D 12 (4.5-9)

Polymixiidae Serranidae 9 (6.5-25)

Poiymixia 2 (21-35) 6 (2.5 - 4.5) Pseudogrammidae 26 (5 -13)

Holocentridae Callanthiidae

Holocentrinae 13 (2.5-12.5) 7 (1.5-2.5) Grammatonotus laysanus 6 (4.5-25) (5.5)

Myripristinae 17 (3.5-8) Symphysanodon 100 (3 - 32)

Zeniontidae Sphyraenidae

Zenion 28 (4 - 38) Sphyraena 42 (4-11) 1 (4.5)

Caproidae Labridae 26 (3-5) 4 (3.5 - 4)

Antigonia 10 (3-19.5) (4) Labrid S 483 (3.5-8) 7 (3-4)

Fistulariidae Labrid B 77 (4-8) 1 (4)

Fistularia 11 (6 - 80) Labrid N 96 (3.5-12) 1 (3.5)

Scorpaenidae 38 (2.5 - 5.5) 4 (3-3.5) Labrid 3 149 (3.5 - 18)

Scorpaeninae 60 (5.5-20) Labrid T 115 (4,5-14.5) 4 (4,5 -6.5)

Scorpaenine E 15 (7-11.5; (5.5) Labrid G 80 (5.5 - 13) 2 (4-5)

Scorpaenine F 12 (8.5 - 16) Labrid X 34 (5.5 - 13.5) 15 (4,5 - 9.5)

Scorpaenodes 21 (5-9) 2 (4.5-8.5) Labrid 0 43 (7.5-17) 1 (10,5)

Dendrochirus barberi 5 (4.5-11) Labrid E 46 (9-21.5) 2 (6-9,5)

Setarchinae 22 (3,5-26) (4) Labrid T' 13 (6-14)

Dactylopteridae 5 (4- 38) Labrid D 9 (5-12.5)

Caracanthidae 2 (8 - 9) Labrid S' 17 (4,5 -7.5)

Acropomatidae Poiylepion russelli 1 (12)

Synagrops 19 (3.5-25) Scaridae

Epigonidae Scarine A 14 (4-7,5)

Epigonus 12 (4.5-33) (4.5) Scarine B 38 (4.5-10) 1 (3)

Apogonidae Calotomus 27 (5.5-17) 1 (6,5)

Pseudamiops 7 (6-9) Pomacentridae 36 (3-6) 13 (3-4)

Apogoninae 36 (3 - 24) Chromis A 9 (8.5 - 15) 1 (14)

Apogonine A 41 (4 - 22) 2 (5 - 5.5) Chromis B 5 (7 -12) 5 (5-14)

Carangidae 267 (2.5-6) 4 (3) Chromis C 4 (9.5-14.5) 1 (11 )

Decapturus 21 (55-16) Plectrogiyphidodon

Selar crumenophthalmus 10 (4.5-8) 12 (4,5-5.5) imparipennis 3 (6.5-13,5)

Scomberoides iysan 4 (5.5-19) 2 (5-6) P. johnstonianus 2 (19-21)

Seriola 13 (5-9.5) Stegastes fasciolatus 5(11.5-14) (5)

Caranx 2 (4) (3,5) Dascyllus albisella 2 (7.5-9,5) (6)

Chaetodontidae Abudefduf abdominalis 1 (6.5)

Chaetodon 37 (3 - 31) Acanthuridae 25 (2-6)

Forcipiger 1 (7) Naso 99 (2.5-37) 18 (1.5-2)

Cirrhitidae 20 (5 - 42) 6 (4,5-7,5) Acanthurus 51 (4- 26)

Lutjanidae Ctenochaetus 53 (6 - 30)

Lutjanus 49 (3 - 10) 2 (3.5 - 4) Zebrasoma flavescens 5 (5,5 - 23)

Aprion virescens 9 (35-5) 1 (4) Champsodontidae

Pristopomoides 11 (3,5-15) 1 (4) Champsodon fimbriatus 8 (5 - 17)

Mullidae 212 (2,5 - 29) 2 (2)
Clarke: Larvae of Nearshore Fishes near Oahu, Hawaii 5

Table 1 (continued)

Size Size Size Size

Taxon No. (mm) No.? (mm) Taxon No. (mm) No.? (mm)

Creediidae Gobiidae (continued)

Limnichthys donaldsoni 1 (10) Goby 0-6 3 (12-14.5)

Crystallodytes cookei 4 (5.5-11) Goby 0-7 1 (6.5)

Percophididae Eviota epiphanes 33 (2.5 -7) 2 (3-4.5)

Chrionema 5 (15-32) Bathygobius 7 (3-6.5) 1 (6)

Bembrops filifera 2 (9- 22) Asterropteryx

Mugiloididae semipunctatus 3 (3-5)

Parapercis 521 (2 -11) 12 (2-3.5) Psilogobius mainlandi 1 (5.5)

Blenniidae 1 (3.5) Kellogia oligolepis 3 (7 -8.5)

Salariini 59 (3-30) 2 (4-4.5) Microdesmidae

Omobranchini 9 (3.5 - 5.5) Ptere/eotris heteropterus 80 (3 -28) 4 (3.5-7.5)

Plagiotremus 3 (21-37) Gunnellichthys curiosus 29 (9 - 40)

Schindleriidae Callionymidae 77 (2-8.5) 2 (2.5-3)

Schindleria praematura 44 (3 -15) (4.5) Callionymid A 69 (2.5-5.5) 2 (2.5-5)

Schindleria pietschmanni 7 (4-12.5) Oraconettidae 1 (30)

Ammodytidae 17 (7.5-23) Tetraodontiformes 2 (3)

Eleotridae Balistidae 8 (3 -60)

Eleotris sandwicensis 90 (3.5 -7.5) 2 (4) Monocanthidae 2 (3-3.5) 1 (3.5)

Gobiidae 30 (4-15) 5 (2.5 - 7) Tetraodontidae 44 (2 - 23) 3 (2-2.5)

Goby A 90 (7 - 25) Oiodontidae 21 (2.5 - 20) 1 (3)

Goby B 55 (5.5-12 1 (4.5) Ostraciidae 4 (2 - 21.5) 2 (2)

Goby 0-3 37 (5.5 -10.5) 4 (8.5 -10) Unident. A 6 (11 -18) 1 (4)

Goby 0-5 42 (4.5-11.5) 3 (8-10.5) Unident. B 7 (5-21)

Goby R 13 (7 -10.5) 2 (5.5) Unident., postflexion 26 (3-15)

Goby C 3 (7-8.5) Unident., preflexion 550 (1-7)

Table 2

Ranks by number of specimens captured, numbers captured, and cumulative percentages of total nearshore

fish larvae for the 20 most abundant families (left columns) and the 20 most abundant lower taxa (right columns) taken in samples from oceanic waters near Oahu, Hawaii, 1977-78.

Families Lower taxa

Rank No. Cum. % Rank No. Cum. %

1. Labridae 1222 23.6 1. Parapercis 521 10.0

2. Parapercidae 521 33.6 2. Labrid S 483 19.3

3. Serranidae 400 41.3 3. Luzonichthys earlei 260 24.4

4. Gobiidae 334 47.7 4. Synodus 169 27.6

5. Carangidae 332 54.1 5. Labrid 3 149 30.5

6. Acanthuridae 251 58.9 6. Labrid T 115 32.7

7. Mullidae 212 63.0 7. Centropyge L3 102 34.7

8. Synodontidae 203 66.9 8. Symphysanodon 100 36.6

9. Scorpaenidae 177 70.3 9. Naso 99 38.5

10. Pomacanthidae 157 73.3 10. Labrid N 96 40.4

11. Callionymidae 148 76.2 11. Eleotris sandvicensis 90 42.1

12. Microdesmidae 113 78.4 12. Goby A 90 43.8

13. Symphysanodon 100 80.3 13. Ptere/eotris heteroptera 80 45.3

14. Eleotridae 90 82.1 14. Labrid G 80 46.9

15. Apogonidae 86 83.7 15. Labrid B 77 48.4

16. Scaridae 81 85.3 16. Serranid A 70 49.7

17. Pomacentridae 76 86.8 17. Callionymid A 70 49.7

18. Blennidae 74 88.2 18. Goby B 55 52.2

19. Lutjanidae 73 89.6 19. Ctenochaetus 53 53.2

20. Schindleriidae 52 90.6 20. Acanthurus 51 54.2
6 NOAA Technical Report NMFS 101

Table .'3

Estimated densities of frequently collected taxa of nearshore fish larvae in the upper 100 m of oceanic waters near Oahu, Hawaii,

1977-78. Densities were calculated from catches of three different nets: a 3-m lsaacs-Kidd mid-water trawl (IK), 1.25-m diameter

bongo nets (BB), and 70-cm diameter bongo nets (SB). Values are not given for cases where the total catch was 5 individuals.

Densities based on all sizes or cruises are indicated by "all." Otherwise, inequalities under "Size" indicate inclusion of only

large or small sizes of certain taxa, and cruise numbers (see text) under "Cruise" indicate separate consideration or exclusion

("x") of data from certain cruises with exceptionally high catches (see text).

Density Density

(No.l1000 m' (No.l1000 m'

Size ----------- Size

Taxon (mm) Cruise IK BB SB Taxon (mm) Cruise IK BB SB

Synodus all all 0.031 0.456 0.604 Labrid B all all 0.023 0.152

all 77-11 0.094 1.577 Labrid N all all 0.024 0.212 0.217

<28 all 0.024 0.450 0.604 Labrid 3 all all 0.039 0.320 0.362

<22 all 0.019 0.358 0.604 all 78-03 0.134 1.221 0.695

Apogoninae all all 0.015 0.190 0.314 <7 all 0.007 0.130 0.217

Carangidae all all 0.097 0.559 0.942 >11 all 0.040 0.271 0.121

all 78-10 l.408 7.330 17.478 Labrid T all all 0.026 0.266 0.362

all x78-10 0.014 0.433 0.276 Labrid G all all 0.015 0.179 0.411

Lutjanus all 77-08 0.060 1.560 Labrid X all all 0.009 0.119 0.242

Mullidae all 77-08 0.094 2.618 55.594 Naso >6 all 0.028 0.038

all x77-08 0.015 0.126 0.601 Acanthurus all 78-02 + 03 0.035 0.481

<10 all 0.014 0.342 2.488 Ctenochaetus all 78-02 + 03 0.111 0.298

>9 all 0.006 0.027 0.048 Parapercisall all 0.116 1.324 1.256

Centropyge all all 0.065 0.119 0.217 all 77-11 0.661 4.730 11.592

all 78-03 0.245 Eleotris sandvicensis all all 0.023 0.190 0.169

<8 all 0.007 0.103 0.121 Goby A all all 0.028 0.163 0.121

>7 all 0.058 0.016 Goby B all all 0.009 0.174 0.121

Luzonichthys earlei all all 0.078 0.380 0.894 Goby D-3 all all 0.010 0.087

>20 all 0.040 0.098 0.097 Goby D-5 all all 0.009 0.103 0.121

all 78-6 0.462 3.933 9.401 Ptereleotris heteroptera all all 0.022 0.114 0.411

<12 all 0.028 0.266 0.773 >11 all 0.007 0.060 0.145

Serranid A all 78-03 0.362 Gunnellichthys curiosus all all 0.007 0.065

Symphysanodon all all 0.033 0.163 0.121 >19 all 0.006 0.027

all 78-03 0.309 0.698 Callionymidae all all 0.027 0.336 0.628

Labrid S all all 0.094 1.433 0.942

all 78-07 0.073 3.183

ranges is not merited. Results for the more frequently taken

taxa are presented in the following individual accounts.

Synodontidae

The great majority ofsynodontids were Synodus (Table 1).

These were taken on all but one cruise, but densities were

markedly higher than average on 77-11 (Table 3) when

over a fourth of the specimens were taken. There was,

however, no significant difference in size composition

between the 77-11 specimens and those /l'om the remainder

of the cruises. The overall median length was 17 mm and

75% of the specimens were between 10 and 26 mm.

Although the IK caught all but one of the 14 specimens

over 27 mm, there was no significant difference in size composition between IK and BB catches (Fig. 1). The estimated

density from the BB data was considerably higher than that

from the IK. Larvae from the SB catch were significantly

smaller in size than those from the BB catch (Fig. 1), and

the largest in the SB catch (21 mm) was only 4 mm longer

than the median size for the BB catch. For larvae <22 mm,

the estimated density from the SB catch was almost twice

the BB estimate.

Trachinocephalus myops was taken between August and

March. Only one specimen was taken by the SB. The IK

captured 9/11 of specimens over 22 mm, while the BB

captured the same fraction of those 22 mm or less. The

remaining synodontids taken were either definitely or

probably small Saurida.

Ophidiidae

Neither of the two types of ophidiid larvae were taken frequently (Table 1). For both, sizes between small larvae and

nearly transformed individuals were absent. Fourteen of

the Brolula multibarbata were 3-13 mm long, while the
________________________ Clarke: Larvae of Nearshore Fishes near Oahu, Hawaii 7

Zeniontidae

Holocentridae

remaining four were 26-60 mm. Five specimens of ophidiid

X were 6.5-15 mm and the other nine were 27-40 mm.

Ophidiid X may prove to be either a pelagic or deep benthic rather than a nearshore species.

Carangidae

All but one of the carangid larvae were taken from July

through November. The great majority were taken on

78-10, and estimated densities for that cruise were much

higher than for the other cruises (Table 3). About 80 %

ofthe carangids were small (2-6 mm). Based upon pigmentation, body shape, and head spination, all but five ofthese

were almost certainly either Decapturus, four species of

which occur in Hawaii, or Selar crumenophthalmus. Both

genera are coastal pelagic and, particularly for Decapturus,

spawning could occur well away from shore. Among the

most cruises, but not in large numbers. The remaining

scorpaenines all had the same fin ray counts (D = XII, 9;

A = III, 5; PI = 16, or rarely 17, 18) and could belong to

any of the genera known from Hawaii except Scorpaenodes.

There were obviously a great many forms among these

specimens, but only two could be reliably distinguished on

the basis of body pigment. All but one specimen of scorpaenid E were taken between November and March, and

all but one of scorpaenid F in February or March.

A distinct form attributed to Dendrochirus barberi on the

basis of fin ray counts was taken in a few samples. The

remaining scorpaenids were Setarchinae. Four of these

(4.5-9 mm) were Setarches sp. The others were either

definitely or tentatively Ectreposebastes. (Some individuals

less than 5.5 mm could not be definitely identified.)

Ectreposebastes imus is a deep-water species which migrates

well off the bottom at night (Struhsaker 1973); adults have

occasionally been taken in IK tows at depths between

ca. 500 and 1000 m in the same study area.

Apogonidae

Other than a few specimens of Pseudamiops taken between

July and November, the apogonids collected (Table 1) were

all apogonines that were not identifiable to species. At least

four different forms were taken, but the distinguishing

features, principally body shape and pigment on the fin

rays, appeared to become less useful with increasing size.

Consequently, many larger specimens and those with

damaged fin rays could not be assigned to one ofthe forms.

Apogonine A, an elongate form, was represented by about

40 specimens 4-22 mm long. Twenty of these were taken

in 77-08, but the rest were scattered throughout the year.

A stubbier form (possibly Apogon erythrinus) was represented

by at least 10 individuals 3.5-10 mm long; these captures

were scattered throughout the year. Two other forms, intermediate in body shape and similar to each other, were

represented by six or fewer individuals. The size ranges

of apogonines captured were about the same for both BB

and IK, but the BB density estimate was much higher than

the IK's (Table 3). Those captured by the SB were mostly

4-6 mm individuals.

SYNODUS

--IK

<>-<> .... e>-<> BB .-_._-. SB

10 20 30 40

STANDARD LENGTH (mm)

10

8 "....,

""" '-"

>- 6 u

z

w

a 4 w

cr

l.L

2

0

0

Zenion was taken on two-thirds of the cruises; captures were

scattered throughout the year. Almost half the specimens

taken (13) were> 13 mm long and taken by the IK. Two

large specimens (30 and 38 mm) were females carrying

vitellogenic oocytes. Thus it is not certain that Zenion should

be considered a nearshore species.

Figure 1

Size frequencies of larvae of Synodus caught by a 3-m Isaacs-Kidd

midwater trawl (IK, solid line, small solid circles), 1.25-m diameter bongo nets (BB, longer dashed line, large open circles), and

70-cm diameter bongo nets (SB, shorter dashed line, small solid

circles) in oceanic waters near Oahu, Hawaii, 1977-78.

Holocentrine larvae were taken only inJuly, August, and

September. Seven specimens (tentatively identified) were

small (1.5-2.5 mm), early preflexion larvae taken on 77-08.

Ten of the 17 myripristine larvae were taken in October,

but the remainder were scattered throughout the other

cruises.

Scorpaenidae

Scorpaenids <5.5 mm long could not be reliably identified

beyond family, but, like the larger larvae, most were

probably Scorpaeninae (Table 1). Among the larger scorpaenines, Scorpaenodes spp., which were distinguishable by

the parietal spines and dorsal spine counts, were taken on
8 NOAA Technical Report NMFS 101 _

Pomacanthidae

Figure 2

Size frequencies of larvae of Centropyge caught by a 3-m IsaacsKidd midwater trawl, 1.25-m diameter bongo nets, and 70-cm

diameter bongo nets in oceanic waters near Oahu, Hawaii,

1977-78. Format as in Figure 1.

All pomacanthid larvae were apparently Centropyge (Table

1). For sizes between 5 and 15 mm, a darkly pigmented

form (L3) with the third dorsal spine much longer than

the fourth could be clearly discriminated from a paler form

(S3) with the third spine only slightly longer than the

fourth. There were no differences among smaller individuals, and the differences in pigment and relative dorsal

spine length were often less clear in larger, near-metamorphic specimens. Dorsal/anal fin ray counts of Centropyge L3 were 15-17/16-17 (rarely 18); most individuals

were either 15/16 or 16/17. Counts for Centropyge S3 were

16-17/17-18, with most counts 17/17 or 17/18. Based upon

available meristic data for Hawaiian Centropyge, L3 is

probably C. fisheri, a deep-water species, and S3 is probably C. polleri, the common shallow-water species.

Centropyge L3 was taken far more frequently than S3 and

on all but two cruises. (About a third of the L3's were,

however, taken in 78-03.) Centropyge S3 was taken only from

February throughJuly; 12 ofthe 17 total were from 78-03.

The small Centropyge, identifiable only to genus, were taken

only in May, August (both years, 19 of the total of 26

specimens), and October (both years). Most of the Centropyge (pooled data) were large individuals; 76% were >7

mm long. All but seven of these were caught by the IK.

The size composition of the IK catch was significantly different from those of either the BB or SB (Fig. 2). While

the latter two nets caught most of the larvae < 7 mm long,

the largest larva caught by the SB was only equal to the

25

CENTROPYGE

--IK

G-<I <>- 0-<> BB .-_._~ SB

5 10 15 20

STANDARD LENGTH (mm)

15

..........

""*" '---'10

>-

U

Z

w

::>

a

w

0:: 5 I.J.-

Over half (130) of the mullid larvae were small «5 mm)

individuals taken by BB or SB tows. These were most

abundant in 77-08 (Table 3) when 139 of the mullids were

taken; 69 and 35 were taken in single SB and BB tows,

respectively. The 78-10 and 78-11 cruises caught 18 and

33 mullids, respectively. The remainder, including all sizes,

were scattered throughout the rest of the cruises. Presumably owing to extrusion through the IK and BB meshes,

the SB density estimates were much higher than for the

larger nets. Even if only the mullids >9 mm were considered, the SB density estimates were by far the highest

and the IK's the lowest (Table 3).

Lutjanid larvae were taken almost exclusively in the late

summer and fall. Over two-thirds of the Lutjanus larvae were small (3-5.5 mm) individuals taken in 77-08

when density estimated from the BB was over 1/103m3

(Table 3). One small individual was taken in June and two

in July. The larger ones were taken from August through

October of both years. All Aprion virescens were taken in

August, and Pristopomoides larvae were taken from July

through October.

Mullidae

Lutjanidae

Except for a single larva of Forcipiger, all chaetodontid larvae

were apparently Chaetodon. Dorsal and anal counts from

31 large, undamaged individuals were XII-XIII, 21-24

and 111,17-20, respectively. Most were XIII, 21-23 and

III, 18-19. While species or even species groups could not

be discriminated by counts, clearly several of the Hawaiian

species of Chaetodon with higher counts were not represented

in the samples. Chaetodon larvae were taken on all but four

of the cruises, but 16 were taken on 78-03 and 78-04. Seven

of the total of eight with twelve dorsal spines were taken

on 78-02 or 78-03. Most Chaetodon were taken by IK; the

BB, however, caught four of the five specimens <6 mm

long. The remaining specimens were almost completely

separated into two size groups: 11 (8-12 mm) and 19

(19-31 mm). Seven of the smaller group were the specimens with twelve dorsal spines taken in February or

March.

larger larvae, both genera were identified based on fin ray

counts (Table 1). Pigmentation differences indicated that

at least two forms of Decapturus were present. Scomberoides

lysan was taken in a few samples, and several larvae of

Seriola were taken in a single sample from 78-10. The more

strictly demersal types of carangids were represented by

only two and possibly three small Caranx larvae.

Chaetodontidae
________________________ Clarke: Larvae of Nearshore Fishes near Oahu, Hawaii 9

25 LUZONICHTHYS

~~ 78-06

<>-<>-0-<>-<> OTHERS

20

"II: -----

'-../ 1

(:) 15 ,\

,\ Z

W 1\

, 8 10 I

cr I

i..L I

I

5 ,

I

I

, 0

0 5 10 15 20 25 30 35

STANDARD LENGTH (mm)

Figure 3

Size frequencies of larvae of Luzonichthys earlei taken in June 1978

(solid line, small closed circles) and all other cruises (dashed line,

large open circles) in oceanic waters near Oahu, Hawaii, 1977-78.

median sized IK catch (12 mm). Only two BB specimens

were > 12 mm. Not surprisingly, the SB and BB gave

higher estimated densities than the IK for the small Centropyge larvae, but the IK appeared to sample the large larvae

much more effectively (Table 3).

Serranidae

The most frequently taken serranid was the anthiine, Luzonichthys ear/ei. (Larvae of this species, identified as "probably Anthias sp." are illustrated by Leis and Rennis 1983,

fig. 17.) It was taken on every cruise, but 50 % of the total

catch was of relatively small individuals taken inJune. The

June larvae from all three types of gear were dominated

by 7-11 mm individuals, which made up 64% of the catch

(Fig. 3). Larvae ofthis size were a minor fraction of catches

from the rest of the year; 77 % of those from other cruises

were metamorphic or apparently metamorphosed individuals >20 mm long. As might be expected, the small Luzonichthys ear/ei were more effectively sampled by the SB and

BB (Table 3). Even for large larvae and juveniles from all

cruises, the BB and SB estimates were similar and considerably higher than that from the IK data. The maximum

size captured by the SB was only 2 mm smaller than the

largest IK specimen.

Four forms ofserranid larvae were probably Anthias. Serranid A was taken only from December through March;

65 of the 70 specimens were from 78-03. All but four

Serranid A larvae were relatively large (10-18 mm).

Serranid A' was very similar to Serranid A and was represented in the samples by only three small and questionably

identified specimens. On the basis of other material from

the study area, particularly six large individuals taken in

May 1974, it appears distinct from Serranid A. All known

captures of this form were from May through August. Both

these forms have nine anal rays. On the basis of dorsal ray

counts, Serranid A is probably Anthias ventralis and Serranid A' is probably A. fucinus. Serranid Band Serranid C

both have seven anal rays, and were very distinct from each

other. Serranid B was taken at almost all times ofthe year,

while Serranid C was taken only from February through

July. Based on fin ray counts, the former is probably

A. bicolor, and the latter, A. thompsoni.

The only other serranid form taken more than a few

times, Serranid D, was taken throughout most of the year.

This form, whose fin ray counts were most similar to those

of Odontanthiasfuscipinnis, apparently metamorphoses at a

smaller size than the above serranids; the largest specimens

already appeared metamorphic and several had scales. At

least five other types of serranid larvae were taken. Except for one damaged specimen whose counts were those

of Liopropoma, all others were anthiines, but had counts not

directly attributable to any known Hawaiian species. There

were also several types among the small, pre-flexion

serranid larvae taken. Many showed some resemblance to

Serranids B, C, or D, but direct "links" between small

specimens and the series of larger individuals were not

available. Surprisingly, almost none of the small, preflexion

serranid larvae appeared likely to be Luzonichthys ear/ei, the

most frequently taken serranid larvae.

Pseudogrammidae

All but one pseudogrammid larvae had fin counts of

Pseudogramma polyacantha. Most (80 % ) ofthe specimens were

taken in either 78-02 or 78-03, but the others were scattered throughout the year. A single larva with counts of

either Aporops or Suttonia was taken in 78-08.

Symphysanodon

Almost 70 % of the Symphysanodon larvae were taken in

78-03; 1-8 individuals were taken on 10 other cruises scattered throughout the year. The size composition of the

March catch differed significantly from that of the remaining catches. The former was dominated by 11-16 mm larvae, while the latter were mostly <8 mm (Fig. 4). The BB

data provided higher estimates of density than did the IK

(Table 3). The SB was apparently effective at catching only

the small larvae, and caught none at all on the peak 78-03

cruise. Three much larger Symphysanodon (50-56 mm) were

taken in the study area by a 5-m IK trawl sample in May

1974. Gill raker counts on these indicated they were

S. maunaloae.

Sphyraenidae

Sphyraena larvae were taken on only seven cruises and

mostly in the fall (33% in 77-08 and 42% in 78-10). Most
10 NOAA Technical Report NMFS 101 _

Labridae

were taken by the BB, but the size composition from all

three types of gear was similar.

Figure 4

Size frequencies oflarvae of Symphysanodon taken in March 1978

(dashed line, large open circles) and all other cruises (solid line,

small closed circles) in oceanic waters n,~ar Oahu, Hawaii,

1977-78.

IK for Labrids Band N; the SB estimate for the latter was

similar to that of the BB (Table 3).

The most frequently taken labrid of the tribe ]ulidini

was Labrid 3 (probably Pseudojuloides cerasinus, if. Miller

et al. 1979, as "Labrid L-3"). Labrid 3 was taken on all

but 4 cruises, but density was markedly higher than

average on 78-03 (Table 3). Size composition overall was

bimodal with about 30 % ofthe larvae in the 4-6 mm range

and over 50 % > 11 mm (Fig. 5). The SB provided the

highest density estimate for the small larvae. The BB provided a higher estimate than the IK for larvae > 11 mm,

but there was a significant difference between the two nets

in size composition of the catch. The IK catch was

dominated by larger larvae than that of the BB (Fig. 5).

Labrid T (either Thalassoma or Gomphosus, if. "Thalassoma" of Leis 1983) was taken on all cruises, but 75 % of

the specimens were taken from 77-10 to 78-03. Size composition of larvae from this period was similar to that of

the remaining larvae. Most Labrid T larvae and almost

all >6 mm were taken by IK or BB. There was no difference between the size compositions oflK and BB catches,

but the latter provided a much higher density estimate

(Table 3).

Two forms of the tribe Novaculini were taken regularly.

Labrid G (Cymolutes lecluse) was taken on almost all cruises,

but 75% of the catches were from February through May.

The BB and SB provided much higher density estimates

than the IK (Table 3). The size compositions of Labrid

G from all three nets were similar; catches were dominated

by large, 11 mm, larvae. Labrid X (Xyrichthys) was very

similar in form to Labrid G, and could not be unequivocally discriminated from it until the dorsal fin elements were

complete (or undamaged). This accounted for the large

number of questionably identified specimens in Table 1.

Even including the questionable specimens, Labrid X was

absent from samples from April through]uly, and all but

four specimens were taken either from October through

November (both years) or from February through March.

Four forms of labrid larvae had the same fin counts

(D/A:IX, 12/111, 12) as several genera ofthe]ulidini and

of Novacalichthys. Labrid 0 (if. Leis and Rennis 1983, fig.

49D) was taken in most months, but over half the total

specimens were from 78-02 and 78-03. Labrid E, a very

elongate form, was absent from most of the late summer

and fall cruises and was most frequently taken in 78-03.

(Even in the largest specimens of Labrid E, it was difficult

to discriminate the last dorsal spines from the first dorsal

rays, and the dorsal fin counts could conceivably be XI,

10.) The minimum size captured for both these species was

fairly large compared to the other labrid types. Two other

less frequently taken forms with the same counts were

Labrid T', which was very similar to Labrid T and was

probably one ofthe]ulidini, and Labrid D, a deep-bodied

form. Other, infrequently taken forms were Labrid S',

which resembled Labrid S but had counts of either

G-<l-e-o-e 78-03

-- OTHERS

SYMPHYSANODON

II

\ f \

&CH>J, :=

o-t-4.....>-----1~---6---,->--'--+--~....L-~·_r1-"'~~-<>-<>---'i o 5 10 15 20 25 30 35

STANDARD LENGTH (mm)

10

>- u

i3 5 ::l

o

W

ct:

u...

At least 13 different forms of labrids were represented,

many ofthem by substantial numbers (Table 1). The most

abundant labrid (and second most abundant taxon collected) was Labrid S, probably Cheilinus (if. Leis and Rennis 1983, fig. 49B). It was taken on all cruises. There was

no indication of a seasonal trend in abundance or size composition. The highest density observed, based on BB data

from 78-07, was only about twice the mean (Table 3) and

not markedly higher than that for several other cruises.

Most were taken by IK or BB. Despite the larger volumes

sampled by the IK, the BB caught more individuals than

the IK and provided higher estimates of density than

either the IK or SB (Table 3). Size compositions from the

IK and BB were similar; the peak numbers were at 6-6.5

mm with few <5 mm and none >8 mm. The SB caught

few >4.5 mm.

Two other forms of the tribe Cheilinini were also taken

frequently. Labrid B (probably Cirrilabrusjordan!) was taken

on all but three cruises, but 71 % were taken in either 78-07

or August (both years). Similarly to Labrid S, the largest

specimens were only 8 mm long. Labrid N (Pseudocheilinus

sp.) was taken on all but two cruises. Except for a high

catch on 78-03, most were taken on late summer and fall

cruises. Labrid N apparently reaches considerably larger

sizes in the plankton than either of the two other Cheilinini

taken. The BB provided higher density estimates than the
_______________________ Clarke: Larvae of Nearshore Fishes near Oahu, Hawaii 11

15 LABRID 3 15 NASa

--IK --IK

Goo'''' CHl BB <>-<>+CHl BB

0--0 --SB 0--0--SB ---. ---. . "*' ..... '-"10 I "*' " \ '-"10 II

I I

>-- I \ >-- I I

U U I , Z I \ Z , I 0

w I w I I A

:J \ :J I , I \ 1\ a I a I

w I w I I \ D::: 5 D::: 5 I

I..L.. I I..L.. I \ \ I

I \ I I

I \ I , I

J/ I

, \

, \ "-<l ;"'- 0 0

0 5 10 15 20 0 5 10 15 20 25

STANDARD LENGTH (mm) STANDARD LENGTH (mm)

Figure 5

Size frequencies of Labrid 3 larvae caught by a 300m Isaacs-Kidd

midwater trawl, 1.25-m diameter bongo nets, and 70-cm diameter bongo nets in oceanic waters near Oahu, Hawaii, 1977-78.

Format as in Figure 1.

Labroides or Suezichthys, and a single specimen with counts

of Polylepion russelli.

Scaridae

The most frequently taken scarid larvae were scarines with

relatively round eyes (Table 1). Scarine A had melanophores on the dorsal edge of the caudal peduncle; Scarine

B lacked this pigment. The size ranges of the two forms

overlapped but specimens of Scarine A tended to be

smaller. Thus the scarine larvae could represent only one

form which loses the dorsal pigment at variable size. Both

scarine forms were taken throughout the year, with the

highest catch (12) in 78-03. The scarid larvae with distinctively narrow eyes, presumably Calotomus, were mostly

larger than the largest scarine larvae, but were less abundant. They were taken on all but 5 cruises; almost half the

total were, however, taken in 78-02 or 78-03.

Pomacentridae

Most of the pomacentrid larvae taken (Table 1) were small

(3-6 mm) with fin elements insufficiently developed for further identification; several were only tentatively identifiable

as pomacentrids. Almost all ofthese small larvae were taken

on one of three cruises: 77 -08, 78-03, or 78-11. Larger individuals were identifiable to genus. Chromis A, which

was taken only in 78-02 and 78-03, had counts of either

C. struhsakeri or C. verater. Chromis B, which was taken in

78-02, 78-03,and 78-06, had counts within or close to the

ranges of either C. agilis or C. hanui; some could conceivably

Figure 6

Size frequencies of larvae of Naso caught by a 300m Isaacs-Kidd

midwater trawl, 1.25-m diameter bongo nets, and 70-cm diameter bongo nets in oceanic waters near Oahu, Hawaii, 1977-78.

Format as in Figure 1.

have been C. leucurus. Chromis C were probably either

C. acares or C. vanderbilti. A few specimens each of the

other known Hawaiian pomacentrid genera were taken

(Table 1).

Acanthuridae

Larvae of Naso were taken on almost all cruises but were

more abundant during June-November. Eighteen very

small (1-2 mm), tentatively identified specimens that had

not yet developed the "acronurus" body form were taken

in 78-10 and 78-11. The three largest individuals (one at

37 mm and two at 34 mm) were exceptional catches; the

next largest were 24 mm. Only 5% of the larvae were >20

mm long and only about 25% were over 10 mm. The SB

did not catch any Naso over 6 mm long. The size compositions uf the BB and IK catches were significantly different

and indicated that the IK was more effective for the large

Naso larvae (Fig. 6). For larvae >6 mm, however, the density estimate from the BB was slightly higher than that from

the IK (Table 3). Both dorsal and anal fin ray counts of

64 individuals ranged from 27-30, and did not exclude any

known Hawaiian species. Most counts, however, were

27-29/27-29 indicating that these larvae were most likely

N. unicornis.

Small (~6 mm) acanthurid larvae which could not be

identified to genus were taken in low numbers throughout

most of the year. Except for a few Zebrasoma flavescens, the

larger individuals had either eight or nine dorsal spines.

The former were considered Ctenochaetus and the latter,

Acanthurus in spite of known, but infrequent, overlap in
12 NOAA Technical Report NMFS 101 _

Parapercidae

Parapercis larvae were the most numerous type taken in the

samples. All large individuals with completely formed

dorsal and anal fins were Parapercis schauinslandi, and there

were no indications of more than one form among the

smaller larvae. Parapercis were taken throughout the year.

Catches varied greatly between cruises but without any

apparent seasonal pattern. Highest catches were in 77-0S

(91 individuals), 77-11 (200), and 7S-03 (S7). The high

catches in 77-0S and 7S-03 were largely due to single BB

samples, but all three types of gear and most individual

tows captured higher than average numbers in 77 -11. Size

composition of both IK and BB catches from 77-11 differed significantly from catches by these nets on the remaining cruises. The larvae from 77-11 were dominated by

smaller individuals than those from the rest of the cruises

(Fig. 7).

For data from all cruises, the SB catches of Parapercis

differed significantly in size composition from those of the

IK and BB; larvae >4 mm were relatively poorly represented in the SB data (Fig. 7). The size compositions of

the BB and IK catches were more similar, but still differed

significantly. Larvae 6-S mm tended to be relatively better

represented in the BB data (Fig. 7). The same trend was

present, but not significant, in the 77-11 data alone. For

the pooled data, the BB density estimate was slightly higher

than that of the SB and much higher than that of the IK

(Table 3). For 77-11, the SB estimate was by far the

highest, but was based on only two tows one of which collected 15 Parapercis larvae-almost a third of the total SB

specimens from all cruises.

on 7S-02 or 7S-03, and it was absent from 10 of the 13

remaining cruises. As was the case with Naso, the two

Acanthurus and three Ctenochaetus >20 mm were exceptional

captures; others were all <16 mm long. Size compositions

of the IK and BB catches were similar, but the SB appeared

effective only for the larvae <S mm. For the peak months

(7S-02 and 7S-03), the BB provided much higher estimates

of density than the IK for both genera (Table 3).

PARAPERCIS

<>-C>-<>-O-<l77-11

-- OTHERS

PARAPERCIS

--IK

c>-o ... 0-<> BB

/ I .--.--. SB

\

I 9

\ 1\

\ f \

\ ,

I,

5 10

STANDARD LENGTH (mm)

I

I

I

e

I

o.......~__."_~/~~,......,.~~,......,.~~,......,.__+.._~.,......._.

o

10

50

10

50

60

---

'-"40

>- U

~30

a

w

0:: 20 l.l...

o....... __~___r_..,.-,......,.~..,.-,......,.__i_~T___T_+?I'_r_.,... ...

o 5 10

STANDARD LENGTH (mm)

Figure 7

(Upper) Size frequencies of larvae of Parapercis taken in November

1977 (dashed line, large open circles) and all other cruises (solid

line, small closed circles) in oceanic waters near Oahu, Hawaii,

1977-78. (Lower) Size frequencies of larvae of Parapercis caught

by a 3-m Isaacs-Kidd midwater trawl, 1.25-m diameter bongo

nets, and 70-em diameter bongo nets. Format as in Figure 1.

counts of the two genera. Dorsal and anal ray counts of

41 Acanthurus indicated that one was A. glaucopareius, but

the remainder were within the ranges of almost all

Hawaiian species. Most counts were 25-26/23-25 indicating that species with low counts (A. triostegius aed A.

olivaceus) were represented by few if any larvae. The three

species most likely to have counts within this range were

A. leucopareius, A. nigrofuscus, and A. xanthopterus. Dorsal and

anal ray counts of 40 Ctenochaetus were 25-27 and 23-25,

respectively, and all within the range for C. strigatus. Only

four specimens could have possibly been C. hawaiiensis.

Acanthurus were taken throughout most of the year and

on all but five cruises. Almost three quarters were taken

on 7S-02 or 7S-03. All but five Ctenochaetus larvae were taken

Blenniidae

Most blenny larvae were salariines (Table 1). These were

taken on nine cruises scattered throughout the year, but

over two-thirds of the total were from either 77-0S, 7S-03,

or 7S-11. All but three specimens were either under S mm

or over 15 mm long. The BB caught slightly more of the

smaller group and only slightly fewer of the larger than

did the IK. The SB specimens were mostly small, but the

largest, 27 mm, was almost as large as the largest IK

specimen. Most of the large specimens were taken in 7S-03

and most of the small ones in 77-OS and 78-11. Fin ray

counts, where possible, indicated that most were probably
_______________________ Clarke: Larvae of Nearshore Fishes near Oahu, Hawaii 13

Cirripectes; only two of the 20 counted could possibly have

been Exallias brevis. Some of the small specimens, without

complete dorsal and anal fins, were possibly Istiblennius spp.

Other types of blenny larvae were very infrequent. In

addition to three large Plagiotremus sp., only one small

unidentified blenniid and nine omobranchines were taken.

Eight of the latter were from 77-08.

Schindleriidae

Schindleria praematura was taken on all but four cruises, but

over half (25) were from 77-08. S. pietschmanni was taken

much less frequently (Table 1); six ofthe seven were taken

on 77-08. Within a few km of shore, S. pietschmanni appears to be the dominant species, and both species are

much more abundant and routinely taken (Leis 1982).

Eleotridae

Larvae of Eleotris sandvicensis, a catadromous species which

spawns in brackish water, were taken on all but two cruises,

but appeared to be most abundant in late summer-fall.

Over half were taken on either 77-08,77-09, or 78-11. The

size range taken was very narrow; 80% were 5-6.5 mm

long, and over half were 6-6.5 mm. IK and BB catches

were similar to each other in size composition and dominated by slightly larger larvae than in the SB catches. The

SB and BB density estimates were similar to each other

and far above that from the IK (Table 3).

Gobiidae

Gobiids were one of the most frequently taken families.

The majority belonged to one of four relatively elongate

forms. Goby A, which is probably a species of Oxyurichthys, was the commonest (Table 1). It was taken throughout

the year and on all but five cruises, but catches were concentrated in 78-02 (30 individuals), 78-03 (22), and 77-11

(20). Over 70 % of the total were> 15 mm long. Goby B

(probably O. lonchotus) also occurred throughout the year,

but half were taken on either 78-03 or 77-11. Nearly 75 %

of the larvae were >9 mm long. Goby D-3 and Goby D-5

were very similar forms, but with different fin ray counts;

the counts of each are, however, shared by several species

of Hawaiian gobies. Both forms occurred throughout the

year and on most cruises, but almost 30% of Goby D-3

were taken on 77-11. Size composition and maximum size

caught by the IK and BB were similar for each of the above

four forms, but BB density estimates were considerably

higher (Table 3). For the three forms taken sufficiently

often by the SB, the density estimates were similar to those

from the BB.

Five less frequently taken types of goby larvae could be

identified based on either unique fin counts or previous

descriptions. Four of these-Eviota epiphanes, Bathygobius,

Asterropteryx semipunctatus, and Psilogobius mainlandi-are

known to occur at much higher densities in waters closer

to shore (Watson and Leis 1974; Leis 1982; Miller et al.

1979). Most of the Eviota and Bathygobius and all Asterropteryx were taken in 77 -08. Larvae of none of the above four

species nor of Kellogia oligolepis appear to reach sizes comparable to the four elongate forms.

Goby R, which was taken on only five cruises, was more

robust than any of the other goby larvae and also had a

longer more pointed snout. The latter suggested Fusigobius,

but Goby R's dorsal and anal ray counts were too low.

Among the larvae under unidentified Gobiidae (Table 1),

there were at least four more distinctive, but unidentifiable

forms, none of which were represented by more than three

individuals. Other unidentified gobies either did not exactly fit any of the forms mentioned above or were too

damaged or too small for identification.

Microdesmidae

Ptereleotris heteroptera was taken only during August-March

with highest catches during the fall months. Almost 20%

of the total came from two IK samples with high catches

ofsmall individuals. Over 60 % ofthe specimens were <12

mm long. For both the entire size range and large (> 11

mm) larvae alone, the SB density estimates were higher

than those of the BB and both much higher than that of

the IK (Table 3). Gunnellichthys curiosus was taken throughout the year and on all but four cruises. Over half the larvae

were longer than 20 mm with only two <10 mm. The SB

caught only three Gunnellichthys; the largest was only 15.5

mm. The BB, however, caught almost as many larvae as

the IK and provided a higher density estimate even for the

larger larvae (Table 3).

Callionymidae

Callionymid larvae were taken on all but one cruise. Abundance varied greatly between cruises, but there was no obvious seasonal pattern. There were at least six and possibly

more different forms among the callionymid larvae. None

of the specimens, however, appeared to be Calliurichthys

decoratus, whose larvae are common in shallow inshore areas

(Miller et al. 1979). Accurate counts of dorsal and anal

fin rays were possible only for the largest individuals, and

only one individual, an 8.5-mm Eleutherochir pogognathus

could be identified beyond family on the basis of counts.

In most other specimens with the fins apparently developed, the dorsal/anal ray counts were 8-7/7-9. The commonest form, Callionymid A was distinguished by a

rounder head profile than the others and very light or no

pigmentation until about 5 mm. The other forms were

distinguished solely upon pigment pattern, but intergrades

or questionable individuals were frequent enough that the

data were not tabulated separately. As might be expected
14 NOAA Technical Report NMFS 101 _

for such small larvae, the IK was the least effective and

the SB the most effective sampling gear (Table 3).

Discussion _

Gear Comparisons

For most taxa or size classes oflarvae considered in Table

3, the density estimates from the IK were markedly lower

than those from the BB, and the latter e timates were often

lower than those from the SB. In many cases between gear

differences in density estimates were accompanied by differences in size composition ofthe catch. Such gear specific

differences were not unexpected given that the three types

of gear differed in mouth size, towing speed, and mesh size,

each of which would affect bias due to avoidance or mesh

escapement or both. Bias due to avoidance would be expected to be less for the larger and faster of any two nets,

but bias due to escapement through the meshes would be

greater because of the larger meshes and perhaps, as suggested by Munk (1988), greater towing speed. The degree

of each type of bias would vary with size of the larvae, but

in opposite directions, and both types of bias could be

operating over part or even all size ranges considered.

Based on analyses of the much more abundant myctophids

in the same samples, Clarke (1983) indicated that larvae

less than 6-8 mm long and fish less than 25-35 mm long

were seriously undersampled by the BB and IK, respectively, because of mesh escapement, but that it was unclear

that mesh escapement was serious at larger sizes because

avoidance of the SB and BB, respectively, may have contributed to the apparent superior performance of the larger

nets for larvae or fish larger than the above size ranges.

The same difficulties in interpreting the data on nearshore larvae are exaggerated because of lower densities

relative to volumes filtered-especially by the SB. Nevertheless, most of the between gear differences in estimated

density and size composition appear related to differences

in error due to mesh escapement. This is most nearly certain in taxa such as carangids, mullids, and callionymids,

where the great majority of larvae were small (~6 mm)

and the SB estimates were by far the highest and the IK

estimates by far the lowest (Table 3). Such sizes would be

least likely to avoid the SB, and losses through the meshes

of the BB and especially the IK were almost certainly

substantial. Error due to escapement through the meshes

of the larger net was also indicated in most cases where

there were significant between gear differences in size composition of the catch. In all cases except the IK-BB comparison for Parapercis, the catch from the smaller net was

dominated by smaller fish. The differences in density

estimates and size composition could have resulted from

escapement of the small, more abundant larvae through

the coarser meshes of the larger net. The differences in size

composition could, however, have resulted in part because

of avoidance of the smaller net by large larvae. In some

IK-BB comparisons (e.g., Centropyge and Labrid 3) and

many BB-SB comparisons (e.g., Symphysanodon and even

small forms such as Labrid Sand Eleotris sandvicensis) the

smaller net appeared ineffective at sampling large larvae.

If such bias due to avoidance were operating at the large

end of the size range, it effectively canceled some of the

losses due to mesh escapement for the large nets and means

that densities of small larvae were even more seriously

underestimated than the comparisons of total densities

would indicate.

Several lines of evidence indicate that even the large larvae of many taxa were underestimated by the IK because

of mesh escapement. For several taxa there were no differences in size composition between IK and BB catches,

and for Parapercis, the BB catch was dominated by slightly

larger fish than that from the larger IK. In these cases and

also most comparisons of density estimates of large larvae

only, the BB estimate was still higher than that of the IK.

The IK estimate was higher than the BB estimate only for

large Centropyge and similar to the BB estimate only for large

Naso. Except for such deep-bodied larval types, it appears

that there were substantial losses of all sizes of larvae

through the meshes of the IK. Error due to mesh escapement would normally be expected to decrease with increasing size and result in differences in size compositions

between the BB and IK, but results of Munk (1988) indicate that the higher speed of the IK may have resulted

in a disproportionate increase in loss of larger larvae of

certain taxa. Munk's results indicated that higher speed

increased loss of large herring larvae but did not change

loss rates for the small larvae.

The apparent superior performance of the IK for catching large Centropyge indicates that these robust, well-developed larvae and juveniles were avoiding the BB and certainly the SB. On the other hand, avoidance of the BB was

apparently not a serious problem for the taxa whose density was better estimated by the BB for even large sizes.

As mentioned above there were several taxa for which the

SB appeared ineffective at capturing larger individuals, but

for others, such as Luzonichthys earlei, the SB caught individuals nearly as large as the largest in the IK catches.

The SB provided the same density estimate for large

L. earlei as the BB. Given that the SB and, for many taxa,

the BB tows sampled insufficient volumes to expect many

or any captures of large, relatively rare individuals, it is

possible that avoidance ofthe smaller nets was not a serious

problem for many of the taxa collected.

The above considerations of mesh escapement and

avoidance are admittedly speculative and imprecise because

there were no between gear tests of any single variable such

as net size without confounding differences in other variables, and the diversity of apparent effects of mesh escapement and avoidance is not unexpected given the diversity

in shape, maximum size, and probable swimming and
_______________________ Clarke: Larvae of Nearshore Fishes near Oahu, Hawaii 15

sensory abilities of the many different taxa considered. The

results overall indicate, however, that, except for its ability to sample larger volumes per unit time, the IK used

here was the least effective sampler for most taxa because

of losses due to mesh escapement. Where densities were

high relative to volumes sampled, the SB and BB appeared

to be the most effective nets for small and large larvae,

respectively. Future studies of such larvae should employ

mid-water trawls with finer mesh than normally used, or

perhaps consider scaling up a bongo-type net to a size that

can sample adequate volumes in a reasonable amount of

time. The several indications that avoidance of the bridleless bongo nets was not a serious problem indicate that a

larger version ofthe BB used here might be more effective

overall than a fine-meshed midwater trawl.

Temporal Variation

For many of the abundant taxa, a large fraction of the total

catch was from one or two cruises, e. g., Synodus and Parapercis on 77 -11, and Luzonichthys earlei on 78-06. On 77-08

and 78-03, high catches of several taxa coincided. The

77-08 cruise collected peak numbers of Apogonine A, Lutjanus, and mullids, as well as unusually high (but not maximal) catches of carangids, Sphyraena, pomacentrids, Parapercis, and salariines. The 78-03 cruise (and to some extent 78-02) was marked by high catches of scorpaenids,

Centropyge, serranid A, Pseudogramma, Symphysanodon, several

labrids, scarids, pomacentrids, Acanthurus, Ctenochaetus, and

Goby A. In all the above cases, the catches were higher

than normal for at least three of the four IK samples and

often for the majority of samples of both types of bongos.

(The smaller nets appeared to be ineffective at sampling

certain large forms, e.g., Centropyge and serranid A, and

thus collected few or none even during peak months.) The

high monthly totals consequently did not appear due to

chance encounters with one or two small scale patches of

high density.

Although these occasional, and often coincident, high

catches could conceivably have resulted from peaks in output of eggs and larvae from the benthic populations, many

were more likely the result of recent and more rapid than

usual movement of water into the study area from inshore.

The evidence for this is strongest for 77 -08. First, the high

catches were not repeated in 78-08 or any adjacent months

of either year. Secondly, the high catches of several taxa,

particularly Lutjanus and mullids, were due primarily to

very small, presumably recently hatched larvae. Finally,

several taxa (Crystallodytes cookei, omobranchines, Schindleria

spp., Eviota, Bathygobius, and Asterropterx) taken exclusively

or nearly so on the same cruise are known to occur routinely within a few km ofshore (Leis 1982; Clarke, unpubl.

data). All of these indicate that water from close to shore

had been transported to the study area very recently before

that particular cruise. Unfortunately, insufficient physical

data were collected on any of the cruises to directly test

this hypothesis.

The high catch of small Luzonichthys earlei in 78-06 was

also unlikely due to a seasonal peak in reproduction since

large L. earlei were taken in roughly comparable numbers

throughout the year. Similarly, there were no hints of

seasonality in the data for Parapercis or Synodus that would

correlate with the very high catches of these in 77-11; in

particular, the high catches were not repeated in 78-11.

Recent movement of water from areas of high density

seems the most likely explanation for these peaks, but it

is difficult to explain why such water carried only one or

a few species. Perhaps these were seasons when only a few

species are abundant in nearshore waters. Alternatively,

larval distributions around the islands may be narrowly

zoned and recently transported water may have come from

a zone where larvae of only one or a few taxa were present

at high densities.

Data from 78-03 differed in several respects from that

of other cruises which caught high numbers oflarvae, and

their interpretation is constrained because of inadequate

data from the preceding three months and the lack of

sampling from two different years. With the exception Symphysanodon and salariines, which tended to be larger than

usual, the size composition of most taxa taken in high

numbers on 78-03 did not differ from that from the rest

of the cruises. The 78-02 cruise, when catches of several

ofthe same taxa were also high, was only two weeks earlier

than 78-03, there was no cruise in 78-01, and the BB was

not used on the 77-12 cruise. Thus the high catches could

conceivably have been the tail end of a broader, 2-3 month

long seasonal peak in abundances. This seems unlikely

because most, but not all, of the taxa with peaks in 78-03

were taken regularly throughout the other cruises. None

are known to be more abundant close to shore, but it is

conceivable that the high catches resulted from recent

movement of water into the study area from somewhere

(perhaps further offshore) where these taxa routinely occur

at high densities.

Another possible explanation for the peak catches in

78-02 and 78-03 is that these cruises sampled available

larvae much better because of higher towing speeds. For

unexplained reasons, the towing speeds estimated from

flowmeter data for all gears were considerably higher than

average for these two cruises. (The mean speeds for 78-02

and 78-03 tows with the IK, BB, and SB were about 12 %,

25 %, and 45 %, respectively, higher than the overall

means.) This had the obvious effect of increasing volumes

sampled per tow, but these differences were far from sufficient to explain the high catches. It is, however, possible

that the higher speeds crossed a major "threshold" for

avoidance of all types of gear by the larger sizes of larvae

and that densities of larvae were actually similar to other

cruises, but catches were higher because of reduced error

due to avoidance for all three types of gear.
16 NOAA Technical Report NMFS 101 _

If occasional high catches of some taxa are ascribed to

circulation events, seasonal trends in occurrence or abundance were evident for only a few of the frequently collected taxa. Centropyge S3, serranid A, and Ctenochaetus appeared restricted to the winter and early spring months.

Lut:janus and indeed alllutjanids were restricted to late summer and fall; this pattern has been noted by Leis (1986)

based on catches from a number of different years. Trachinocephalus myops and Ptereleotris heteroptera were taken only

during August through March. Naso and several types of

labrid larvae were taken over all or most of the year, but

abundances were high only over shorter periods. Some of

the less frequently taken taxa, such as holocentrines, also

appeared to be present or more frequent during certain

seasons.

Both the general lack of seasonality in abundance and

most instances of apparent seasonality fail to support

Lobel's (1978) hypothesis that spawning seasons of inshore

fishes are timed to coincide with the period (DecemberJune) when ocean current patterns might favor retention

oflarvae near the islands. The apparent seasonal peaks in

abundance of some labrid larvae agree with seasonal patterns of recruitment of several Hawaiian labrids reported

by Walsh (1987), but otherwise the observed patterns of

larval abundance (or lack thereof) correlate poorly with

Walsh's evidence for a summer peak in recruitment of

many reef fishes.

Size Composition

The very early stages of inshore fish larvae are apparently

only rarely transported as far offshore as the study area.

For the great majority of taxa, the smallest larvae taken

were at either late preflexion or early postflexion stages.

Except for the coastal pelagic carangids, multiple captures

of early preflexion stages occurred in only a few cases:

holocentrines and mullids in 77-08 and Naso in 78-10. Admittedly, it is possible that there were more, but unrecognized early preflexion larvae of nearshore families present

in the samples, but for reasons given in the methods section it is unlikely that the number of misidentifications were

sufficient to substantially alter the above statements.

The largest specimens of the more abundant taxa were

probably close to the maximum size for the pelagic stages.

For the majority of abundant taxa it appeared that all sizes

between late pre-/early post-flexion and the maximum size

were either about equally represented or at least reasonably

likely to occur in offshore waters. Eight types of larvae,

however, were represented primarily by relatively large and

presumably near-settlement size larvae. These were Centropyge, Luzonichthys earlei (except in 78-06), serranid A, labrids

o and E, Calotomus, goby A, and Gunnellichthys. In these

taxa, and perhaps for some ofthe less frequently taken taxa,

even the early to middle postflexion stages appear to be

rarely advected very far offshore.

Four abundant taxa (Chaetodon, Symphysanodon, Labrid

3, and salariines) were exceptional in that the size composition of larvae appeared bimodal. A few of the rarer

taxa (ophidiids, Polymixia, dactylopterids, and tetraodontiforms) also appeared to be represented mostly by either

very small or very large individuals. Bimodal size-frequency distributions could result from periodicity in spawning. Alternatively, the peak of small individuals could

simply represent the most abundant age group while the

peak at larger sizes could represent an accumulation of

older individuals with a wide range of ages, but small differences in size. Victor (1986a) has shown that labrid larvae can delay metamorphosis and continue to grow for long

periods after the probable minimal size and age for settlement has been reached but that growth is greatly slowed

after the latter point.

Densities

The average densities of even the most abundant taxa were

very low (Table 3). Only Parapercis and Labrid S regularly

occurred at levels of 1/103 m3 . Carangids, mullids, and

Luzonichthys earlei occurred at similar or higher densities only

on single cruises. For the many taxa that were taken less

frequently than those in Table 3, the average densities

would be on the order of 0.0001-0.01/103 m3 . Because it

is likely that most taxa do not occur throughout the entire

0-100 m stratum, densities within the actual depth range

would be higher. Even if larvae occurred only within a

10 m deep stratum and densities thus were 10 times higher

within that stratum, filtering a volume of a few hundred

m3 , typical of most plankton tows, would be woefully inadequate. Even a volume of the order of 103 m3 would be

insufficient for all but a few taxa at a few times. As is

illustrated by the results from the SB tows in this study,

such volumes filtered simply would not be expected to catch

most taxa.

Lobel and Robinson (1988) reported densities of 0.3-

6.8/103 m3 for inshore fish larvae at five stations in and

near an eddy off the island of Hawaii. These values are

much higher than most averages reported here and were

exceeded for only a few species on a few cruises. Lobel and

Robinson's results must, however, be interpreted with caution because they are based on few samples. A single surface and a single near-surface tow, each ofwhich apparently

sampled about 1-2 x 103 m3 , were taken at each station.

Consequently, the density for any taxon collected could

not be less than ca. 0.3/103 m3 . The 44 different density

estimates in their table VI are based on only 130 specimens;

23 estimates, apparently on single captures per station.

With the exception of carangids, only two nearshore taxa

were taken in substantial numbers-both at the same station. More data are necessary to determine ifthe reported

densities ofthese two taxa are routinely encountered, if they

are only associated with eddies or similar recent transport
_______________________ Clarke: Larvae of Nearshore Fishes near Oahu, Hawaii 17

from inshore, or if the present study may have ineffectively

sampled near-surface depths (see below).

Sale (1970) reported on larval acanthurids taken by a

large pelagic trawl at two locations close to the area sampled

by the present study. Using estimated towing speed and

mouth opening of this trawl (Higgins 1970), Sale's catch

data indicate that densities of acanthurid larvae were only

0.001-0.002/103 m3, about 100 x lower than those estimated from this study (Table 3). Part of the difference is

due to capture of smaller and more abundant larvae by

the nets used here, but even considering only the same size

range as reported by Sale, the estimates from the present

study are still very much higher. Apparently all sizes of

acanthurids were seriously underestimated owing to escapement through the coarse (19-mm stretch) meshes of the

wings of the large pelagic trawl.

Faunal Composition

The larvae collected represent most offamilies of Hawaiian

inshore fishes, and the most abundant taxa were all from

families that are abundant in the nearshore habitats. Nevertheless, several taxa that appear to be very abundant as

adults in nearshore habitats were poorly represented or absent in the offshore samples. Some common taxa from

shallow water areas which were absent or poorly represented were holocentrids, Kuhlia, Kyphosus, demersal carangids, and pomacentrids other than Chromis. Similar, abundant taxa from slightly deeper but still nearshore areas

(Struhsaker 1973) were Glossanodon, Aulopus, Chlorophthalmus, Polymixia, and Synagrops. The meristics oflarval Acanthurus and Chaetodon indicate that some species, such as

A. triostegis and C. milian's which are very abundant inshore,

were either probably absent or at best poorly represented

among the larvae collected. Although adult abundance inshore is obviously not the sole determinant oflarval abundance offshore, it is difficult to postulate why the above

taxa were so poorly represented. There is no indication that

they differ strongly in fecundity, reproductive output,

spawning mode, or larval development period from related

taxa that were taken frequently. Their absence or rarity

in the present samples may indicate that, even within

genera, larval behavior differs enough to affect degree of

dispersal to offshore waters.

It is also possible that some taxa of inshore fish larvae

were absent or underrepresented in the present samples

because they occur in the upper few m of the water column and were poorly sampled owing to the ship's presence

directly ahead of the nets. With the exception of the

carangids, the most important taxa from the present study

are either absent or relatively poorly represented in Lobel

and Robinson's (1988) data from near surface tows in

oceanic waters off the island of Hawaii. At one oftheir stations, larvae of holocentrids and the pomacentrid Abudefduf abdominalis occurred at very high densities. Neither of

these were taken very frequently during the present study

and may, like some of the other poorly represented taxa,

prove to be more abundant very close to the surface.

The inshore fish larvae from the study area were not

dominated by taxa with relatively large larvae. Although

larvae of several abundant families reach rather large size

(15 mm or more) before metamorphosis, families with small

size at metamorphosis (parapercids, eleotrids, callionynmids) were, if anything, more abundant. Within the most

abundant family, the labrids, there is a great range of maximum sizes oflarval types (Leis and Rennis 1983). Several

forms of labrids taken in this study reach almost 20 mm

as larvae, but the most abundant labrid, Labrid S, and

Labrid B, the sixth most abundant, apparently metamor-

.phose at less than 10 mm.

Although relevant data on larval stage durations are few,

they indicate that at least the labrids taken in the study

area were not dominated by genera with long larval stage

durations. Assuming my generic identifications are correct, the Hawaiian species of the two most abundant

labrids, Labrid S (Cheilinus?) and Labrid 3 (Pseudojuloides?)

have much shorter larval stage durations than those of other

tentatively identified genera such as Thalassoma, Cymolutes,

and Xyrichthys (Victor 1986b). In contrast, available age

data on pomacentrids (Thresher et al. 1989; Wellington

and Victor 1989) indicate that Hawaiian species ofthe most

frequently taken genera-Chromis, Stegastes, and Plectroglyphidodon-tend to have longer larval stage durations than

do the infrequently taken Dascyllus and Abudefduf.

Taxa with unique pelagic "prejuvenile" stages (acanthurids, chaetodontids) or whose larvae possess long spines

(e.g., Symphysanodon) or other apparent modifications for

pelagic existence were abundant in the present samples but

were far outnumbered by labrids, parapercids, gobiids, and

mullids, none of which show obvious special modifications

for pelagic existence. The most abundant serranid larvae,

Luzonichthys earlei, was relatively nondescript and had less

developed spines than most other serranid larvae. While

it is possible that taxa whose larvae are large, long-lived,

or modified for pelagic existence will better survive dispersal offshore, occurrence and abundance in offshore

waters are not well predicted by larval size, duration, or

morphology .

Most of the larvae from this study were of taxa which

spawn pelagic eggs as adults, and the three most frequently

taken families (labrids, parapercids, serranids) are pelagic

spawners. Predominance of larvae of pelagic spawners was

not, however, overwhelming. The demersally spawning

gobiids were fourth in number of specimens, and six other

demersally spawning families (Microdesmidae, Eleotridae,

Apogonidae, Pomacentridae, Blenniidae, Schindleriidae)

were among the top 20 families taken. The observed

dominance of pelagic spawners does not seem surprising

given that most families of inshore Hawaiian fishes are

pelagic spawners. Leis and Miller (1976) reported a similar
18 NOAA Technical Report NMF'S 101 _

dominance by larvae of pelagic spawners in offshore waters

of Hawaii and contrasted this with evidence of dominance

by larvae of demersal spawners in inshore coastal waters.

They concluded from this, without comparison of inshore

and offshore densities, that larvae of pelagic spawners tend

as a group to be more abundant in offshore waters and

those of demersal spawners more abundant close to shore.

Comparison of the results of the present study with those

of Leis (1978, 1982) from inshore waters off the same

coast of Oahu indicate that not only are the conclusions

reached by Leis and Miller (1976) not supported, but also

that their proposed general differences in dispersal patterns

between larvae of demersal and pelagic spawners are questionable. Leis's (1978, 1982) data show that dominance by

larvae of demersal spawners in inshore waters is due to few

species-primarily a tripterygiid, a schindleriid, and a

gobiid. Their densities were much higher than those of any

taxon taken offshore in the present study. Larvae of pelagic

spawners were absent or very rarely taken; however, so

were larvae of most demersally spawning taxa taken in the

present study. Leis and Miller (1976) noted that larvae of

certain demersal spawners (salariine blennies and Chromis)

were apparent exceptions to their proposed trend. In fact,

the few species of demersal spawners which dominate inshore are apparently the exceptions. Smith et al. (1987)

report that inshore areas adjacent to deep water in the

Caribbean are dominated by "clupeids, blennioids, and

gobioids. " Although the number of species involved is not

given, it appears that high abundances ofjust a few types

of larval fishes may characterize inshore waters in other

areas bathymetrically similar to Hawaii.

Furthermore, Leis's results-like those of other studies

of ichthyoplankton in inshore Hawaiian waters-were

based on plankton tows which filtered only a few hundred

m3 per sample. Even if larvae of pelagic spawners and the

"missing" types of demersal spawners had been present

inshore at densities 10-100 x those observed offshore, only

an occasional capture would be expected by such small

volume samples. While small volume samples are adequate

to show that certain taxa are much more abundant inshore

than offshore, inshore waters must be sampled with procedures comparable to the BB or IK tows used in the present study in order to determine if any larval forms or sizes

are ever more abundant offshore than inshore.

If, as hypothesized above, the occasional and often coincident high catches of certain taxa in offshore waters were

due to recent movement of surface waters, then some of

the taxa taken offshore must occur somewhere else at considerably higher densities than usually observed in these

samples. As mentioned above, Schindleria and certain goby

larvae are known to routinely occur at considerably higher

densities within a few km of shore. (Preliminary analyses

ofsamples recently collected off windward Oahu indicates

that certain other taxa such as Lutjanus and holocentrids

are also more abundant closer to shore.) Ifdensities of more

taxa prove to be higher somewhere between the location

of the present study and shore, it may mean that nearshore

larvae which occur more than a few km offshore are normally a minor and perhaps inconsequential fraction oftotal

potential recruits to island populations and are of consequence only for zoogeographic dispersal.

Acknowledgments _

I thankJ.M. Leis and B.C. Mundy for assistance in identifying larvae and G.W. Boehlert for critical review of an

earlier draft of the manuscript. Sample collection and rough

sorting of larvae were supported by NSF OCE77-09202.

Subsequent analyses were supported by the University of

Hawaii, Hawaii Institute of Marine Biology.

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